(a) Field of the Invention
The present invention relates to a hybrid electric vehicle including a turbocharger and a method of controlling driving of the hybrid electric vehicle.
(b) Description of the Related Art
A turbocharger is a forced induction device used to allow more power to be produced for an internal combustion engine of a given size. A turbocharged engine can be more powerful and efficient than a naturally aspirated engine because a turbine forces more intake air, and proportionately more fuel, into the combustion chamber than if atmospheric pressure alone is used.
Turbochargers were originally created for aircraft engines, but in the last few decades have been integrated into vehicular platforms do to their increased energy efficiency. Since turbochargers are easily and simply mounted to a diesel engine, turbochargers have begun to be mounted a plethora of mass-produced diesel vehicles.
Additionally, as demands for a vehicle having improved fuel efficiency increase worldwide, downsizing of even a reduced sized engine displacement has become popular, and as a result, turbochargers have become popular in gasoline vehicles as well.
The efficiency of the engine is determined based upon various factors. In particular, the efficiency of the engine may be determined based on the amount of oxygen provided by intake air flowing into the engine. Accordingly, in order to increase the efficiency of the engine, it is necessary to compress intake air as must as possible, and to this end, the turbocharger is used.
A turbocharger compresses the intake air by utilizing exhaust air discharged from the engine. The exhaust air drives the turbocharger to be discharged to the outside. When the engine rotates at a higher speeds, the exhaust air further includes a large amount of energy even after sufficiently driving the turbocharger. Accordingly, various methods have been researched in order to utilize this energy included in the exhaust air.
Although, turbochargers improve performance of the engine, it is not easy to exhibit the advantageous effects of turbochargers at low speeds and low torque in which the amount of exhaust gas is greatly decreased due to the use of kinetic energy of the exhaust gas.
Furthermore, since oil prices have greatly increased and exhaust gas regulations have become stricter, eco-friendly vehicles and fuel efficiency improvement have been the focus in the development of most vehicles. Accordingly, vehicle makers have made an effort to develop a technology for reducing fuel consumption and decreasing exhaust gas in order to meet eco-friendly regulations and improve fuel efficiency.
Under the above circumstances, the vehicle makers have particularly focused much interest and effort in hybrid electric vehicle (HEV) technology which efficiently combines and uses power of an engine and power of a motor in order to achieve high fuel efficiency.
Hybrid electric vehicles have met purchase demands of many customers due to their high fuel efficiency and eco-friendly image. FIG. 1 illustrates a conceptual configuration of a hybrid electric vehicle.
Referring to FIG. 1, the hybrid electric vehicle may include an engine 10, a driving motor 20, an engine clutch 30 that engages or disengages power between the engine 10 and the driving motor 20, a transmission 40, a differential gear 50, a battery 60, a starting/generating motor 70 that starts the engine 10 or generates power to charge the battery via output from the engine 10, and/or wheels 80.
Further, a hybrid electric vehicle may include a hybrid control unit (HCU) (i.e., a type of controller that includes a processor and a memory) for controlling the entire operation of the hybrid electric vehicle and a battery control unit (BCU) 120 (i.e., also another type of controller that includes its own processor and memory) for managing and controlling the battery 60. The battery control unit 120 may be called a battery management system (BMS). Furthermore, the starting/generating motor 70 may be called an integrated starter and generator (ISG) or a hybrid starter and generator (HSG) in this field of art.
The driving modes of the hybrid electric vehicle may be an electric vehicle (EV) mode, which is a mode in which only power from the driving motor 20 is supplied to the transmission. In a hybrid electric vehicle (HEV) mode, torque from the driving motor 20 is utilized as auxiliary power while using torque of the engine 10 utilized as main power in most hybrid applications. Finally, in a regenerative braking (RB) mode brake and inertia energy is collected through generation from the driving motor 20 to charge the battery 60 during braking or driving using the inertia of the vehicle.
As described above, the hybrid electric vehicle uses mechanically both energy from the engine and electric energy from the battery, uses an optimum operation region of the engine and the driving motor, and collects the energy using the driving motor while braking, thereby improving fuel efficiency and efficiently using the energy.
However, hybrid electric vehicles do not typically include a turbocharger, so that there is a chance to improve fuel efficiency, if a configuration could be found to properly implement the turbocharger into these types of vehicles. However, in the past, the pressure from the exhaust has been insufficient to properly operate a turbocharger.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.